Process of improving compounding characteristics of butadiene-1,3 copolymers by means of nu-halogen amides



Patented Mar. 4, 1947 PROCESS OF IMPROVING COMPOUNDING CHARACTERISTICSOF BUTADIENE-L3 COPOLYMERS BY MEANS OF N-HALOGEN AMIDES Herman ElbertSchroeder, Wilmington, Dei., as-

signor to E. I. du Pont de Nemours & Company, Wilmington, Dcl., acorporation of Delaware No Drawing. Application June 5, 1944, Serial No.538,876

11 Claims.

This invention relates to a method of improving the processingcharacteristics, that is, the ease of mastication and of compoundingoperations, of rubbery diene polymers and copolymers.

It is well known in the rubber manufacturing art that the usefulness ofany rubber-like material depends in part upon the ease with which thismaterial may be worked or milled so that fillers and curing ingredientscan be rapidly and successfully incorporated and dispersed therein. Anumber of compounds, for example thiols and substituted hydrazines havebeen used as processing aids for improving the working and millingcharacteristics of natural rubber. These compounds are onlv moderatelyeffective for this purpose with synthetic rubber and they have certaindisadvantages. for example disagreeable. odor in the thiols and toxicityin the hydrazines,

An object of this invention is to provide a method of improving theworking and milling characteristics of rubbery hydrocarbon polymers,including copolymers, of conjugated diene hydrocarbons so thatprocessing operations prior to vulcanization are materially facilitated.I A further obiect is to provide a class of compounds which increase theease of milling of rubbery hydrocarbon polymers of conjugated dieneswhen added in small amounts. Further objects will appear hereinafter.

These objects are accomplished in accordance with the present inventionby milling, i. e. doing internal work upon, an unvu canized, rubberyhydrocarbon polymer of a conjugated diene mixed with a sma l amount ofan N-halogen amide in which the halogen is chlorine, bromine, or iodinebut preferably chlorine orbromine. Theaddition of as little as 0.1% andpreferably 0.25% to 5% of an N-halogen amide to the rubbery hvdrocar- Ibon polymer of the conjugated diene during milling reduces, by as muchas 85%. the time necessary for break down to a smooth, continuous sheetwhich is capable of readily taking up compounding ingredients.

In the preferred process of this invention a small amount of anN-chloroamide is added to a rubbery hydrocarbon polymer of a conjugateddiene on a rubber mill or in an internal mixer and mastication iscontinued until the rubbery polymer or copolymer becomes soft andplastic. If the process is carried out on a rubber mill, the material ina short time forms a continuous, rolling sheet free from holes. The timerequired for the rubbery polymer or copolymer to reach the state atwhich compounding ingredients are readily dispersed therein is markedlyless than if 2 milling is continued without the addition of theN-chloroamide.

The more detailed practice of this invention is illustrated by thefollowing examples in which parts-are given by weight.

Example I I Twenty (20) parts of a synthetic, rubber-11k copolymerprepared from a mixture of '75 parts of 1,3-butadiene and 25 parts ofstyrenaknown commercially at GR-S. is placed on a six inch rubber millheated to C. and the mill is set so that the opening between the rollsis 18 gauge. Then 0.8 part (4%) of 1,3-dichloro-5-methyl-5-isobutylhydantoin is added to the rubbery material and milling iscontinued. After milling for fifteen minutes, the synthetic rubber formsa smooth, continuous sheet that grips the mill roll firmly, contains noholes and can readily be compounded. Another 20 parts of this same batchof GR-S is milled under exactly the same conditions, but ninety minutesmillin is required before the rubbery material is broken down to acontinuous sheet free from holes and readily compounded. Thus, thepresenceof the 1,3-dichloro-5-methyl- 5-isobutylhydantoin effects a 77%reduction in milling time required to reach the desired state forsatisfactory compounding.

Example II As described in Example I, GR-S is milled with 4% of thefollowing chlorohydantoins as milling aids, in which case 48% to 80%reduction in milling time is obtained over the time required to reachthe same state when no milling aid is added.

Example III GR-S is milled with 4% of N'-chlorophthallmide in the mannerdescribed in Example I. -A reduction in milling time of 81% is obtained.

Example IV As described in Example GR-S is armed with 4% of thefollowins chlorinated sulfonamides and substantial reductions in millingtime are obtained in every case.

Per cent Compound reduction in milling time N,lNT-dichloro-p-toluanesulfonumirlov l7N,N-dichlorom-curboxyhcnzencsulionumidn iii Zinc salt ofN,N-dichioro-p-carboxybcuzenesulfonomide illButane-l,4-bis(suliondichloroamido) iii) Propane-l3-bis(N,N-dichlorosulfonamide) 75 N, N,N,N"-tetmchlorocyclohexanedlsulionamldc-l ,4 78

This invention is generic to the milling of, i. e.

the doing of internal work upon, a rubbery hydrocarbon polymer of anacyclic conjugated diene hydrocarbon mixed with an N-halogen amidehaving the group Halogen wherein X is CO or S02, and the halogen ischlorine, bromine, or iodine but preferably chlorine or bromine.Included in this case are the N-chlorocarbonamides. e. g.N-chloroacetamide, N-chlorohexanamide, N-chlorododecanamide,N-chlorooctadecanamide; the N-chlorohydantoins of the formula:

wherein R and R are hydrogen or hydrocarbon and Y is hydrogen chlorine,bromine, or iodine.

Compounds of this type are illustrated in Examples I and II.

pounds are:

N-chloro-5-methyl-5-amylhydantoin,1,3-dichloro-5-methyl-5-amylhydantoin,N-chloro-5-methyl-5-phenylhydantoin, N-chloro-5-n-butylhydantoin,N-chloro-5-ethyl-5-phenylhydantoin, andN-chloro-5-methyl-5-cyclohexylhydantoin.

Other halogen compounds which may be used include N-bromoacetamide,N-bromooctadecanamide, N-bromo-5,5-dimethylhydantoin,1,3-dlbromo-5-methyl-5-isobutylhydantoin, N-iodoacetamide, andN-iodopropionamide.

Also included in this class are the N-chlorosulfonamides as illustratedin Example IV. Additional N-chlorosulfonamides areN,N-dichloron-butanesulfonamide-l, N,N-dichlorobenzenesulfonamide,N,N-dichloromethanesulfonamide, and N chioropropanesulfonamide 1. Othercompounds useful in this invention are the N-chloroimides, illustratedby Example 111.

The unvulcanized rubbery hydrocarbon polymers of conjugated dienes, themilling charac- Additional illustrative comferred since improvements inmilling characteristics are most marked with these elastomers whentreated in accordance with the process of this invention. The process ofthe invention is also applicable to copolymers of conjugated dienehydrocarbons containing major amounts of 1,3- butadiene or isoprene andminor amounts of non hydrocarbon vinyl or vinylidene compounds, forexample acylonitrile, methyl methacrylate, dimethyl(vinylethinyhcarbinol, methyl betavinylacrylate, vinylidene chloride,methyl vinyl ketone and vinylpyridine, but the results with thesepolymers containing elements other than carbon and hydrogen are by nomeans as satisfactory as are the results with hydrocarbon polymers.

The processing aids of this invention may be used at temperaturesbetween 25 C. and C. The N-chloroamide may be added to the rubberyhydrocarbon polymer as a powder, or it may first be dissolved in asuitable solvent, for example esters, e. g. ethyl acetate, triacetin,butyl sebacate; ethers, e. g. ethylene glycol monomethyl ether, ethyleneglycol dimethyl ether, diethylene lycol monomethyl ether, dioxane;alcohols, e. g. isopropyl alcohol; chlorinated hydrocarbons, e. g.chloroform. The improvement in milling and working properties of therubbery hydrocarbon polymers through the addition of the N-chloramidesis particularly evident when these compounds are incorporated in thediene polymer on a rubber mill. Improved working properties are alsoobtained however when the diene polymers or copolymers are mixed withthe chloramides by other means, for example in an internal mixer.

Small amounts, for example from 0.25% to 5% of the N-chloramides byweight, based on the weight of the diene polymer or copolymer used,

are sufiicient to reduce the time necessary for milling of the polymericmaterials to obtain the physical state where they may be readilycompounded with compounding ingredients, for example fillers and curingagents. On a rubber mill, this point is reached when the rubberypolymeric material forms a smooth, continuous sheet free from holes,soft, and with good tack. Larger amounts of the N-chloramides can beused, but these do not usually offer any advantages over the use ofsmaller amounts, An outstanding advantage of the use of theN-chloramides used in connection with the rubbery diene polymers andcopolymers is that they reduce the time required for the fabrication ofuseful articles from these polymers, the total power requirements inmilling, and allow greater production of finished goods per unit ofequipment. Furthermore, only small amounts are necessary so that whilethe ease of milling of the rubbery polymer is greatly improved, theproperties of the final vulcanizates are not materially affected by theaddition of these compounds.

Although this invention has been described primarily in terms of the N-chloroamides, other ha]- ogen derivatives, for example the bromine andiodine derivatives are also eifective. The bromine and chlorinederivatives are preferred.

The above description and examples are intended to be illustrative. Anymodification of or variation therefrom which conforms to the spirit ofthe invention is intended to be included within the scope of the claims.

What is claimed is:

1. Process for bringing a hydrocarbon polymer of butadiene-1,3 intocondition for the incorporamasticating a mixture of said polymer and asmall amount, of the order of 0.25 to 5%, based on the weight of thepolymer, of an N-halogen amide wherein the halogen is selected from theclass consisting of chlorine, bromine, and iodine,

2. Process for bringing a butadiene/styrene copolymer having a majorproportion oi. butadiene- 1,3 into condition for the incorporation ofcompounding ingredients which comprises' masticating a mixture of saidpolymer and a small amount, of the order of 0.25% to 5.0%, based on theweight oi? the polymer, of an N-bromoamlde.

3. Process for bringing a hydrocarbon polymer of butadiene-1,3 intocondition for the incorporation of compounding agents which comprisesmasticatlng a mixture of said polymer and a small amount, of the orderof 0.25 to 5%, based on the weight of the polymer, of an N-chloroamide.

4. Process for bringing a hydrocarbon polymer of butadiene-1,3 intocondition for the incorporation of compounding agents which comprisesmilling a mixture of said polymer and a small amount, of the order of0.25 to 5%, based on the weight of the polymer, of an N-halogen amidewherein the halogen is selected from the class consisting of chlorine,bromine, and iodine on a rubber mill until the milling sheet iscontinuous, free from holes, soft, and tacky.-

5. Process for bringing a hydrocarbon polymer of butadiene- 1,3 intocondition for the incorporation of compounding agents which comprisesmilling a mixture of said polymer and a small amount, of the order oi.0.25% to 5.0%, based on the weight of the polymer, of an N-bromoamide.

6. Process for bringing a hydrocarbon polymer of butadiene-1,3 intocondition for the incorporation of compounding agents which comprisesmilling a mixture of said polymer and a small amount, of the order of0.25 to 5%, based on the weight of the polymer, of an N-chloroamide on arubber mill until the milling sheet is continuous, free from holes,soft, and tacky.

7. Process for bringing a butadlene/styrene copolymer having a majorproportion of butadiene- 1,3 into condition for the incorporation ofcom- Number -2,41e,eea

pounding ingredients which comprises masticating a mixture 0! saidpolymer and a small amount, of the order oi! 0.25 to 5%, based on theweight of the polymer, of an N-halogen amide wherein the halogen isselected from the class consisting oi. chlorine, bromine, and iodine.

8. Process for bringing a butadiene/styrene copolymer having a majorproportion of butadiene- 1,3 into condition for the incorporation ofcompounding agents which comprises masticatlng a mixture of saidcopolymer and a small amount,

, of the order of 0.25% to 5%, based on the weight of the copolymer, ofan N-chloroamide.

9. Process for bringing a butadiene/styrene copolymer having a majorproportion of butadiene- 1,3 into condition for the incorporation ofcompounding agents which comprises masticating a mixture of saidcopolymer and a small amount, of the order of 0.25% to 5%, based on theweight of the copolymer, of an N-chlorohydantoin.

10. Process for bringing a butadiene/styrene copolymer havinga majorproportion of butadiene-1,3 into condition for the incorporation ofcompounding agents which comprises masticating a mixture of saidcopolymer and a small amount, oi! the order of 0.25% to 5%, based on theweight of the copolymer, of an N-chloro-5,5-dialkylhydantoin.

11. Process for bringing a butadiene/styrene copolymer having a majorproportion of buta- (Ilene-1,3 into condition for the incorporation ofcompounding agents which comprises masticatlng a, mixture of saidcopolymer and a small amount, of the order of 0.25% to 5%, based on theweight of the copolymer, of a 1,3-dichloro-5,5-dialkylhydantoin.

HERMAN ELBERT SCHROEDER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PA'I'ENTS Name Date 2,325,947 Garvey Aug. 3, 1943

